In message . com, at
14:09:49 on Thu, 22 Jun 2017, "dennis@home"
remarked:
Subsidence would not be a feature of such new builds.

I wouldn't be so sure of that..
I have been shown a new estate where they built about 20 houses and
sold them and then started building the next phase.
At this point cracks started to appear in the first phase.
It turns out that all the houses had started to move and the developer
was now desperately trying to find ways to stabilise the ground.
The last time I looked they had demolished some of the first phase and
were piling the ground near the houses (not for foundations).

Built on a landfill site, perhaps?
--
Roland Perry